> We are annotating nodes on a hierarchical structure > where NULL implied an
I don't mean to be rude, but yuck. Why provide a record for data that isn't there?
No offence taken - I'm trying to improve an old (partially inherited) system, hence the original post.
I have no idea if this model would work for you, but maybe it will help.
That approach all sounds sensible, however going through the links that Richard Broersma sent over in a previous post - I'm currently leaning towards the flexibility and intuitive interface that ltree contrib module appears to offer.